Calculation of thermodynamic properties and transport coefficients of Ar-C-Si Plasma

Abstract

In this paper, the composition, thermodynamic properties and transport coefficients of the argon-carbon-silicon plasma at local thermodynamic equilibrium(LTE) and local chemical equilibrium(LCE) for a wide range of temperatures (300 K – 30000 K) and pressures (0.1 atm - 10 atm) and different mixture ratios are presented. The condensed phases and Debye–Hückel corrections are both taken into account. The equilibrium component in gas phase is calculated by mass action law (Saha’s law and Gulberg–Waage’s law), Dalton's partial pressure law, conservation of the elements and charge quasi-neutral equation, while the condensed species is calculated by the local phase equilibrium assumption. Thermodynamic properties include density, enthalpy and specific heat are evaluated through a classical statistical mechanics approach. Transport coefficient calculations include viscosity, electrical conductivity, and thermal conductivity using a third-order approximation (second-order for viscosity) of the Chapman-Enskog method. Collision integrals are obtained using the relatively new data. The results show that the concentration and ratio of C\Si vapor has a great influence on the properties of the Ar plasma by introducing not only the C\Si vapor’ s own properties, but also new reactions. While the pressure influence those properties by the shift of chemical equilibrium and the changes of total number density. In addition, the introduction of condensed species makes the thermodynamic properties and transport coefficients of the lower temperature plasma are almost the same as those of pure argon, and causes discontinuous points at phase-transition temperature. The final calculation results are in good agreement with the literature comparison, and the difference is due to the different use of collision integral. The results are expected to provide reliable basic data for the numerical simulation of argon-carbon-silicon plasma.